$\dfrac{9}{5} - \dfrac{8}{6} = {?}$
$ = {\dfrac{9 \times 6}{5 \times 6}} - {\dfrac{8 \times 5}{6 \times 5}} $ $ = {\dfrac{54}{30}} - {\dfrac{40}{30}} $ $ = \dfrac{{54} - {40}}{30} $ $ = \dfrac{14}{30}$